#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;
int main()
{
    int n, p;
    cin >> n >> p;
    vector<int> nums(2 * n, 0);
    long long sum = 0;
    for (int i = 0; i < 2 * n; i++)
    {
        cin >> nums[i];
        sum += nums[i];
    }
    long long tmp = sum;
    sort(nums.begin(), nums.end());
    for (int i = 0; i < n; i++)
    {
        sum -= nums[i];
    }
    long long sum2 = tmp - sum;
    long long ans = 0;
    if (p > 50)
    {
        ans = (100 - p) * sum2 + p * sum;
    }
    else //p<=50
    {
        long long t = 0;
        for (int i = 1; i < 2 * n; i += 2)
        {
            t += nums[i];
        }
        ans = (100 - p) * (tmp-t) + p * t;
    }
    if (ans % 100 == 0)
    {
        cout << ans / 100 << endl;
    }
    else
    {
        cout << ans << "%" << endl;
    }
}